Damper operating arrangement



May 26, 1964 w. v. MILLMAN 3,

DAMPER OPERATING ARRANGEMENT Filed Aug. 51, 1961 INVENTOR.

WILLIAM V. MILLMAN BY {M A ATTOR N E Y United States Patent 3,134,318 DAMPER GPEEATKLJG ARRANGEMENT William V. Miliman, Molina, ill, assignor to American Air Fitter Company, line, Louisville, Ky 21 corporation of Delaware Fiied Aug. 31, 1961, Ser. No, 135,341 6 Claims. (Ql. 98-68) This invention relates to an improved damper operating arrangement for unit ventilators and the like.

In Hubbard US. Patent 2,723,616 there is disclosed a damper operating mechanism for the outdoor air damper and a room air damper of a unit ventilator wherein two crossed links extend between the crank arms for the two dampers and cooperate therewith to interconnect the dampers for concurrent, inverse relation positioning under normal conditions, with the arrangement being such that under a condition of the outdoor air damper being open to at least a predetermined degree, the room air damper will close under the force of a gust of wind entering through the outdoor air inlet.

The airangement of the present invention is intended to accomplish essentially the same result, but contemplates a somewhat simpler construction of the operating mechanism.

In accordance with the invention, a single link interconnects the cranks and a lost motion connection is made between the ends of the link and the respective cranks. The connection between the outdoor air damper crank and link is such that the link can both swivel and slide relative to a fixed point on the crank, while the connection between the room air damper crank and the other end of the link is such that a fixed point on the link can both pivot relative to the crank and move toward or away from the axis of rotation of the room air crank. In the herein disclosed embodiment of the invention, one link end has a lengthwise extending slot which receives a pin carried near the outer end of the outdoor air damper crank, while the other end of the link carries a pin which is received within a slot running generally lengthwise along the room air damper crank, the latter slot having one end relatively close to the pivotal axis of the crank.

With this arrangement, when the outdoor air damper is closed the pin on the outdoor air damper crank engages one end of the link slot and forces the link and room air damper crank to a position where the room air damper is substantially open. Conversely when the outdoor air damper is fully opened, the pin on the outdoor air damper crank engages the other end of the link slot and pulls the link and room air damper crank to a position where the room air damper is closed. However since the slot in the room air damper crank has its inner end relatively close to the room air damper pivotal axis as compared to the distance between the pin on the outdoor air damper crank and its pivotal axis, a position of the outdoor air damper in a range from slightly open to fully open permits movement of the room air damper to a fully closed position when necessary to block the passage of outdoor air gusts. 1

The invention will be described in somewhat greater detail in connection with the accompanying drawing wherein is illustrated a preferred embodiment by way of example, and wherein:

FIGURE 1 is a partly diagrammatic view of a damper operating arrangement embodying the present invention in a position wherein the outdoor air damper means is closed and the room air damper is open;

FIGURE 2 is an enlarged View of a part of the damper operating mechanism in an intermediate position;

FIGURE 3 is a view similar to FIGURE 2, but with the damper operating mechanism in a position wherein "ice the outdoor air dampers are fully open and the room air damper is fully closed.

The damper operating arrangement of the invention may be incorporated in unit ventilators of various construction. For example, while the illustrated damper arrangement includes a pair of oppositely rotating outdoor air dampers and is used in a ceiling mounted unit ventilator, a similar damper operating arrangement may be used for a unit ventilator having a damper construction including a single outdoor air damper as shown in the noted Hubbard patent. It is assumed that those parts of the unit ventilator not shown are of generally conventional construction in the sense that it has a central compartment through which the air flows and in which the damper, heat exchange means and fans are situated, and has at least one end compartment in which the damper operating mechanism, fan motor, and certain conventional control elements are situated, the central air flow compartment and the end compartment being separated by suitable partition means.

Referring to the drawing the damper section is located within the central compartment of the unit ventilator and is in communication with a source of outdoor air through wall inlet 2 and with the served room through recirculation inlet 4, the unit ventilator being horizontally dis posed immediately below a ceiling 6 with its base against the side wall 8 having inlet 2. The outdoor air damper means comprises a pair of oppositely rotatable balanced dampers 19A and 10B mounted on shafts 12A and 1233 respectively for rotation therewith. The shafts 12A and 12B are journalled, at opposite ends, in suitable bearings carried by the opposite respective partitions 14 (one shown) which separate the end compartments from the central air flow compartment of the unit ventilator.

Recirculation or room air damper 16 is fixed to shaft 18 which is also journalled in bearings carried by the opposite partitions 14. This damper includes a counterweight 20 carried along the radially closer longitudinal edge of the damper to substantially balance the damper so that within the limits of positioning dictated by the damper operating mechanism, the room air damper is self-positioning in accordance with air fiow conditions.

When the various dampers are moved to closed positions, their longitudinal edges are adapted to seal against air flow therearound by engaging suitably disposed seats which extend across the central compartment parallel to the damper shafts between the partitions 14 and all of which seats are designated by the numeral 21.

Whatever air is admitted into the damper section exits therefrom through an air filter 22 and then through the remainder of the central compartment containing one or more heat exchangers, perhaps additional dampers of a face and bypass character, and the fans which induce the air flow through the unit. The flow of air into the damper section from outdoors and from the room is indicated by the solid line and broken line arrows respectively. It is to be understood that while the terms outdoor air and room air are herein used the invention is also applicable to a situation where the socalled outdoor air is not taken directly from the outside of the building but is rather of a different temperature character than the room or recirculation air.

Since the separate outdoor :air dampers NA and 13B are positively linked to operate together in opposite rotational directions, attention will be directed primarily to the operating mechanism and relationship between the lower of these two dampers and the room air damper 16. However, first the means for driving the outdoor air dampers 10A and 16B will be considered in connection with FIGURE 1.

A damper operator (not shown) is connected to rotate shaft 2 one way or another in accordance with the temperature demands of the served room. This rotational motion of shaft 24 is transmitted to upper outdoor air damper 1013 through crank arm 26 which is rigidly fasened to shaft 24 for rotation therewith, and through short link 23 pivotally fixed at one end to arm 26 and at the other end to arm 36 which is fixed to shaft 12B. Rotational motion of the lower outdoor air damper 16A in an opposite rotational direction to 19B is simultaneously imparted from crank arm 26 through long link 32 pivotally connected at opposite ends to crank arm 26 and arm 34, the latter arm being rigidly fastened to outdoor air damper shaft 12A. The shaft 24 also has rigidly fastened thereto another crank arm 36 which is pivotally connected to a link 33 leading to additional dampers of the face and bypass type in a part of the unit ventilator not shown.

Returning now to that par-t of the damper operating mechanism of primary concern, another crank arm 44 is rigidly fixed to outdoor air damper shaft 12A for rotation therewith and serves as the driving arm for link 42 connected on one end to crank 40 and on the other end to arm 44 which is rigidly fastened to effect rotation of room air damper shaft 18. The crank 44 carries a pin 46 thereon which is received within link slot 48 extending along the link 42 longitudinal axis at one end thereof. The other end of link 42 has attached thereto a pin 50 which is received within arm slot 52 of arm 44. The pins are held within the slots by suitable means such as a washer and cotter key arrangement (not shown). It will thus be understood that as to the driving relationship between outdoor air damper 19A and room air damper 16, the outdoor air damper is the positively positioned element, and the room air damper 16 normally is the driven element which follows the outdoor air damper positioning in inverse relation thereto.

In the FIGURE 1 position, the outdoor air damper A is closed and the room air damper 16 is held substantially open by crank pin 46 engaging the one end of link slot 48 and the link pin Stl engaging the radially inner end of arm slot 52. It will be appreciated that the force of air flow through the room air inlet 4 against the room air damper 16 is normally a factor tending to hold the room air damper in a more or less open position. However, when the outdoor air damper moves to a fully open position, the room air damper is then forced to a fully closed position, the linkage force overcoming the air force. In any event the room air damper will be held in a position which is open to at least the extent shown in FIGURE 1 when the outdoor air damper is fully closed, it being understood that the room air damper may assume a somewhat more open position depending upon the force of the air flow through the room air inlet.

In FIGURE 2 the outdoor air damper NA has been positively moved to a slightly open position so that some outdoor air is admitted into the unit. The room air damper 16 (shown in FIG. 2 in both its upper, open position corresponding to the solid line positions of the arm 4-4 and link 42, and its lower, closed position corresponding to the broken line positions of the arm 44 and link 42) will reposition itself toward a less open position since the force of the air through the room inlet 4 against the room air damper is reduced, and crank pin 46 is moved out of engagement with the inner end of link slot 48 so that the link 42. can move upwardly as required under the force of arm slot 52 against link pin 50 as the room air damper moves toward a closed position.

In FIGURE 3 the outdoor air damper 10A has moved to a fully open position and the room air damper 16 has been forced to a fully closed position. In this case the crank pin 46 engages the outer end of link slot 8 to move link 42 to its uppermost position, and the link pin 50 at the other end of link 42 engages the radially outer end of arm slot 52 and forces the arm 44 in a clockwise direction to close the room air damper.

Returning now to FIGURE 2, the outdoor air damper 10A is shown as being opened just enough that if a sufficiently forceful gust of outdoor air enters the damper section, the room air damper may be forced to a closed position. In that case the link 42 and arm 44 assume their broken line positions wherein the link 42 has moved upwardly under the force of arm slot 52 engaging the link pin 52, and the pin St has moved to the inner end of arm slot 52. It is to be understood that arm 44 and link 42 move to their broken line positions corresponding to the room air damper being fully closed as a result of the room air damper being forced to a closed position by a gust of wind. That is, the closing movement of the room air damper causes the movement of the arm 44 and link 42 under such a condition rather than the movement of the arm 44 and link 42 causing movement of the room air damper. Rotation of the room air damper from the substantially open to a closed position without movement of the out door air damper to a fully open position is possible because the radial distance between the crank pin 46 and the pivotal axis of shaft 12A is several times greater than the radial distance between the inner end of arm slot 52 and the pivotal axis of shaft 18.

The relationship which permits this desired operation is perhaps best explained using one example of the invention as embodied in commercial apparatus. Assume that the distance between the centers of pin 46 and shaft 12A is three inches and the distance between the center of the inner end of arm slot 52 and shaft 18 is Vs inch, and that when the outdoor air damper is closed the room air damper is held in an open position which requires that it rotate through 45 to a closed position. Then using the mensuration formula for the length of a chord subtended by an angle, it may be calculated that when the room air damper moves through the 45 clockwise rotation to a closed position, the corresponding length of chord between the two positions of the inner end of arm slot 52 will be about /3 inch. By rotating the outdoor air damper to a limited degree from a fully closed position, the pin 46 will have moved sufiiciently upwardly, and away from the pivotal axis of shaft 18, that movement of link pin 5% the /3 inch to the room air damper closed position may be accommodated. In the one commercial apparatus noted, rotation of the outdoor air damper at least 10 from a closed position permits the room air damper to operate to a closed position if necessary.

It will be appreciated that the desired operation noted may be obtained with other damper arrangements by varying the relationship of the elements influencing the operation, such as the angular disposition of one crank relative to the other in a position of the outdoor air damper being closed, the spacing between the shafts 12A and 18, and of course the difference in spacing between pin 46 and shaft 12A and between the inner end of slot 52 and shaft 18.

In the normal inverse relation positioning of the dampers NA and 16, the room air damper positions itself, throughout a considerable part of its range of operation, in accordance with air flow conditions through the damper section without restriction by the linkage. Thus, as illustrated in FIGURE 2, as the outdoor air damper 10A is progressively opened the crank pin 46 moves up the slot 48 and the room air damper 16 will not be positively moved toward a closed position by the link 42 until pin 46 engages the upper end of slot 48. When the outdoor air damper is moved from the fully open position (FIGURE 3) back toward a closed position, the link pin 50 will move from the outer end of slot 52 toward the shaft 18 as the link is permitted to drop, the curved outer end of slot 52 urging the pin 50 in a direction toward shaft 18 so that any tendency of the pin 50 to hang up in the outer end of the slot is avoided.

I claim:

1. In apparatus for controlling rotation of a first and a second damper in normally inverse relation while permitting said second damper to operate to a closed position throughout a major portion of the open position range or" said first damper: first and second crank means fixedly connected to said first and second dampers respectively for corresponding rotation therewith; a single link intercomiecting said cranks; means connecting one end of said link to a fixed point on said first crank for both pivotal movement therebetween and limited movement of said link in a generally longitudinal direction; means connecting the other end of said link to said second crank for both pivotal movement therebetween and limited movement of a med point on said other end in a generally longitudinal direction along said second crank to a point on said second crank relative to the pivotal axis of said second damper at least.three times as close as the spacing of said fixed point on said first crank to the pivotal axis of said first crank.

2. In a damper controlling arrangement for normally positioning a unit ventilator outdoor air damper and a room air damper in inverse relation while permitting said room air damper to close throughout a major portion of the open position range of said outdoor air damper: a damper operating crank fixed to effect rotation of each of said dampers about its respective axis of rotation; at single link interconnecting said cranks for said inverse relation positioning, including first lost motion connecting means connecting one end of said link to a fixed point on said outdoor air damper crank to permit swivelling movement and limited reciprocating. movement of said link relative to said outdoor air damper crank fixed point, and including second lost motion connecting means connecting a fixed point on the other end of said link to said room air damper crank for swivelling movement therebetween and limited movement of said link fixed point toward and away from said axis of rotation of said room air damper crank.

3. In a damper controlling arrangement for normally positioning an outdoor air damper and a room air damper of a unit ventilator in inverse relation while permitting said room air damper to operate to a closed position throughout a major portion of the open position range of said outdoor air damper: a damper operating crank fixed to efiect rotation of each of said dampers about its respective axis of rotation; a single link interconnecting said cranks; means connecting one end of said link to a radially fixed point on said outdoor air damper crank for pivotal and limited reciprocating motion of said link relative to said point; and means connecting a fixed point on the other end of said link for pivotal movement relative to said room air damper crank, and for movement along said room-air damper crank generally toward and away from said axis of rotation of said room air damper crank, the minimum spacing as measured between said link fixed point and said axis of rotation of said room air damper crank being no more than /3 the Y spacing as measured between said outdoor air damper crank fixed point and said axis of rotation of said outdoor air damper crank.

4. In apparatus for controlling rotation of a first and second damper in normally inverse relation while permitting said second damper to rotate to a closed position throughout a major portion of the range of ro tation of said first damper: a rotatable first crank having one end fixed to efiect rotation of said first damper about its rotational'axis and having a pin connector at its other end; a rotatable second crank fixed to effect rotation of said second damper about its rotational axis and having a slot therein extending generally radially outwardlly, the inner end of said slot being relatively close to said rotational axis of said second damper as compared to the spacing between said first crank pin connector and said rotational axis of said first damper; a single link connecting said first and second cranks, said link having a longi tudinally extending slot at one end engaging said first crank pin connector, and a pin connector at the other end engaging said second crank slot; the dimensional relationships between the recited elements being such that the length of are through whichsaid inner end of said second crank slot passes as said second damper rotates from a substantially open to a closed position is less than /3 of the length of arc through which said first crank pin connector passes as said first damper rotates from a closed to a fully open position.

, 5. The apparatus of claim 4 wherein said second crank slot is curved at its outer end toward said first crank.

6. In a damper arrangement for controlling the ad mission of air into a unit ventilator from an outdoor air source and a room air source: a rotatable room air damper and a rotatable outdoor air damper mounted on respective individual shafts and adapted for concurrent operation in inverse relation under normal air entry conditions; a first crank fixed to said outdoor air damper shaft and a second crank fixed to said room air damper shaft, both cranks extending in the same general direction in opposite extreme positions of said dampers, said first crank having a pin adjacent its outer end, and said second crank having a slot therein extending generally lengthwise along said second crank; a link interconnecting said cranks including a pin at one end slidably engaging said second crank slot, and a slot at the other end slidably engaging said first crank pin; said crank, link and slots thereof being so dimensioned that when said outdoor air damper is fully open said room air damper is held closed by said link pin means engaging the outer end of said second crank slot and, when said outdoor air damper is fully closed, said room air damper is held substantially fully open by said link pin means engaging said second crank slot, with said second crank free to move to a position closing said room air damper upon rotation of said first crank to an, outdoor air damper open position exceeding a predetermined minimum.

References Cited in the file of this patent UNITED STATES PATENTS 2,723,616 Hubbard Nov. 15, 1955 2,828,110 Baker et al. Mar. 25, 1958 3,019,987 Goeniann et al. Feb. 6, 1962 3,034,725 Person May 15, 1962 

1. IN APPARATUS FOR CONTROLLING ROTATION OF A FIRST AND A SECOND DAMPER IN NORMALLY INVERSE RELATION WHILE PERMITTING SAID SECOND DAMPER TO OPERATE TO A CLOSED POSITION THROUGHOUT A MAJOR PORTION OF THE OPEN POSITION RANGE OF SAID FIRST DAMPER: FIRST AND SECOND CRANK MEANS FIXEDLY CONNECTED TO SAID FIRST AND SECOND DAMPERS RESPECTIVELY FOR CORRESPONDING ROTATION THEREWITH; A SINGLE LINK INTERCONNECTING SAID CRANKS; MEANS CONNECTING ONE END OF SAID LINK TO A FIXED POINT ON SAID FIRST CRANK FOR BOTH PIVOTAL MOVEMENT THEREBETWEEN AND LIMITED MOVEMENT OF SAID LINK IN A GENERALLY LONGITUDINAL DIRECTION; MEANS CONNECTING THE OTHER END OF SAID LINK TO SAID SECOND CRANK FOR BOTH PIVOTAL MOVEMENT THEREBETWEEN AND LIMITED MOVEMENT OF A FIXED POINT ON SAID OTHER END IN A GENERALLY LONGITUDINAL DIRECTION ALONG SAID SECOND CRANK TO A POINT ON SAID SECOND CRANK RELATIVE TO THE PIVOTAL AXIS OF SAID SECOND DAMPER AT LEAST THREE TIMES AS CLOSE AS THE SPACING OF SAID FIXED POINT ON SAID FIRST CRANK TO THE PIVOTAL AXIS OF SAID FIRST CRANK. 